If a paladin uses the staggered mercy on himself as a move action does he gain a standard action?
So you wouldn't do this as a move action.
A paladin uses Lay on Hands as a Standard Action, except on himself where its a swift action. Thankfully, you can still use your swift action when staggered so no worries there.
As to the question of whether or not you would regain your other action type...
Assuming you do your swift action mercy first to remove staggered, I see no reason why you shouldn't be allowed to have al your actions that turn.
Yeah sorry meant swift. My brain kind of fritzed. I'm playing the insinuator antipaladin so I get mercies (and self only lay on hands) and one of my traits is Beaten Not Broken so I got back up from negative. Layed on hands and my dm goes and says my turn is over.